我们再来一次，我仍然在上面的问题上撞墙。 我有一个datasframe，我通过csv上传，看起来像：
X SPY VTI
01.02.2002 0.0000 0.0000
04.02.2002 -2.4578 -2.4167
.....
31.12.2015 -1.003 -0.9685
其中X是日期，SPY和VTI是股票收益
我尝试了很多东西来转换成时间序列。首先我试过
spyvti$X <- as.Date(as.character(spyvti$X),format="%d.%m.%Y.")
我得到的是：
X SPY VTI
NA 0.0000 0.0000
NA -2.4856 -2.4167
.....
NA -1.003 -0.9685
所以看起来它不能在类（Date）的对象中转换第一列，这是一个因素。
我还尝试将data.drame分成3个不同的向量，首先将日期向量转换为字符，然后才能工作，然后
date <- as.Date(date, format = "%d.%m.%Y.")
error in charToDate(x):
character string is not in a standard unambiguous format.
所以我想帮助克服日期问题，并且我想知道，当日期问题结束时，创建一个ts对象是否正确
tsobject <- xts(date,spy)
其中spy是数字。
非常感谢
保
答案 0 :(得分：0)
使用“lubridate”包。它使日期的转换变得非常容易。
library(lubridate)
dmy(spyvti$x)
答案 1 :(得分：0)
我正在想起这件事。希望它有效。您可以尝试以下方法：
public class MainActivity_d3 extends AppCompatActivity implements AdapterView.OnItemSelectedListener {
//Declaring an Spinner
private Spinner spinner2, spinner1;
private String str_spinner1, str_spinner2, s_name, s_course;
//An ArrayList for Spinner Items
private ArrayList<String> students1;
private ArrayList<String> students2;
Button mBtnSave;
//JSON Array
private JSONArray result1, result2, result;
//TextViews to display details
private TextView textViewName1;
private TextView textViewName2;
private TextView textViewCourse;
private TextView textViewSession;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mainactivity_d1);
//Initializing the ArrayList
students1 = new ArrayList<String>();
students2 = new ArrayList<String>();
//Initializing Spinner
//Adding an Item Selected Listener to our Spinner
//As we have implemented the class Spinner.OnItemSelectedListener to this class iteself we are passing this to setOnItemSelectedListener
spinner1 = (Spinner) findViewById(R.id.spinner1);
spinner2 = (Spinner) findViewById(R.id.spinner2);
spinner1.setOnItemSelectedListener(this);
spinner2.setOnItemSelectedListener(this);
// spinner1.setOnItemSelectedListener(this);
mBtnSave=(Button)findViewById(R.id.button2);
mBtnSave.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String str_spinner1 = spinner1.getSelectedItem().toString();
String str_spinner2 = spinner2.getSelectedItem().toString();
}
});
//Initializing TextViews
textViewName1 = (TextView) findViewById(R.id.textViewName1);
textViewName2 = (TextView) findViewById(R.id.textViewName2);
// textViewCourse = (TextView) findViewById(R.id.textViewCourse);
// textViewSession = (TextView) findViewById(R.id.textViewSession);
//This method will fetch the data from the URL
getData1();
getData2();
}
@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
if(spinner1.getId()==R.id.spinner1) {
str_spinner1 = spinner1.getSelectedItem().toString();
}
else if(spinner2.getId()==R.id.spinner2)
{
str_spinner2 = spinner2.getSelectedItem().toString();
}
/* switch (view.getId()){
case R.id.spinner1:
getData1();
break;
case R.id.spinner2:
getData2();
break;
}*/
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
if (spinner1.getId() == R.id.spinner1) {
//do this
textViewName1.setText("");
} else if (spinner2.getId() == R.id.spinner2) {
//do this
textViewName2.setText("");
}
}
private void getData1() {
//Creating a string request
StringRequest stringRequest1 = new StringRequest(Config.DATA_URL1,
new Response.Listener<String>() {
@Override
public void onResponse(String response1) {
JSONObject j1 = null;
try {
//Parsing the fetched Json String to JSON Object
j1 = new JSONObject(response1);
//Storing the Array of JSON String to our JSON Array
result1 = j1.getJSONArray(Config.JSON_ARRAY1);
//Calling method getStudents to get the students from the JSON Array
getStudents1(result1);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error1) {
}
});
//Creating a request queue
RequestQueue requestQueue1 = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue1.add(stringRequest1);
}
private void getStudents1(JSONArray j1) {
//Traversing through all the items in the json array
for (int i = 0; i < j1.length(); i++) {
try {
//Getting json object
JSONObject json1 = j1.getJSONObject(i);
//Adding the name of the student to array list
students1.add(json1.getString(Config.TAG_COURSE));
} catch (JSONException e) {
e.printStackTrace();
}
}
//Setting adapter to show the items in the spinner
spinner1.setAdapter(new ArrayAdapter<String>(MainActivity_d3.this, android.R.layout.simple_spinner_dropdown_item, students1));
}
//Initializing TextViews
// textViewCourse = (TextView) findViewById(R.id.textViewCourse);
// textViewSession = (TextView) findViewById(R.id.textViewSession);
//This method will fetch the data from the URL
private void getData2() {
//Creating a string request
StringRequest stringRequest2 = new StringRequest(Config.DATA_URL2,
new Response.Listener<String>() {
@Override
public void onResponse(String response2) {
JSONObject j2 = null;
try {
//Parsing the fetched Json String to JSON Object
j2 = new JSONObject(response2);
//Storing the Array of JSON String to our JSON Array
result = j2.getJSONArray(Config.JSON_ARRAY);
//Calling method getStudents to get the students from the JSON Array
getStudents2(result);
} catch (JSONException e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error1) {
}
});
//Creating a request queue
RequestQueue requestQueue2 = Volley.newRequestQueue(this);
//Adding request to the queue
requestQueue2.add(stringRequest2);
}
private void getStudents2(JSONArray j2) {
//Traversing through all the items in the json array
for (int i = 0; i < j2.length(); i++) {
try {
//Getting json object
JSONObject json2 = j2.getJSONObject(i);
//Adding the name of the student to array list
students2.add(json2.getString(Config.TAG_USERNAME));
} catch (JSONException e) {
e.printStackTrace();
}
}
//Setting adapter to show the items in the spinner
spinner2.setAdapter(new ArrayAdapter<String>(MainActivity_d3.this, android.R.layout.simple_spinner_dropdown_item, students2));
}
}
答案 2 :(得分：0)
假设您的示例数据框名为df，您可以将其转换为xts时间序列对象，如下所示：
library(xts)
xtsObject <- as.xts(df[,-1],order.by = as.Date(as.character(df[,1]), format = "%d.%m.%Y"))